Build-in electric field induced step-scheme TiO2/W18O49 heterojunction for enhanced photocatalytic activity under visible-light irradiation

Artificial Z-scheme heterostructure photocatalysts, inspired by the natural photosynthesis, have been explored for water contamination owing to the efficiency of charge carriers separation and enhanced redox capacity. Herein, a novel step-scheme TiO2/W18O49 heterojunction integrating TiO2 nanosheets and spindle-like W18O49 was prepared via a two-step solvothermal method. The TiO2/W18O49 heterojunction with the optimum ratio exhibited excellent photodegradation of RhB higher by a factor of 2.26 and TC degradation higher by a factor of 3.32 than the pristine TiO2 when exposed to visible light. The reactive free radical trapping experiment indicated center dot O-2(-) was determined to the dominant reactive species. Furthermore, XPS analysis and center dot O-2(-) quantification measurements confirmed a build-in electric field induced step-scheme structure in TiO2/W18O49 composites, which effectively enhanced the separation of carriers, thus improved photocatalytic activity. The present study will offer a new perception related to the formation of step-scheme heterostructure for photocatalytic degradation.